Genetic and phenotypic parameters for productive traits in white egg layer stocks

Abstract

Information on 2054 CC and 1514 DD White Leghorn layer chicken lines from the CNPSA-EMBRAPA, in Concórdia, SC, Brazil, were used to estimate heritability (h²) and genetic (rp) and phenotypic correlations (rp) for average egg weight (PMO), egg production rate from 23 to 40 weeks of age (TP), and egg mass from 35 to 40 weeks of age (MO). Incubation (I), sire (R) within line (L) and female within R whithin L significantly affected all traits. Least square means for PMO, TP and MO were, respectively, 56.4 g; 83.3% and 2.122 g for CC and 56.0 g; 82.3% and 2.107 for DD. The estimates of h and rg indicate that individual selection applied in line CC and family selection applied in line DD would improve TP the most. In both lines, however, selection for PMO is necessary in order to avoid reducing the size of the eggs.